Replacing OEM batteries with LiFePO4's

casmith32

Member
To my knowledge as of today nothings changed with respect to charging in freezing temperatures


Sent from my iPhone using Tapatalk
 

israndy

2007 LTV Serenity
Don't most battery packs have a heating element that the charger would use to heat the battery pack in the winter before allowing any charing to occur? Seems that is what the RoadTrek guy told me about their setup.

I just wonder how Tesla handles this situation, you don't have an alternator running on another fuel to provide the electricity to heat the pack before you go driving. But if I can draw from it down to -22 degrees, that would cover MOST driving conditions. They must have a way that when I plug it in they do SOMETHING to allow it to warm the battery with the charging plug before it takes a charge.

-Randy
 

Peter Tourin

2020 Unity RL, ex 2012 Unity MB
Tesla - I've assumed, without knowing anything definite, that they have temp sensors within the batteries, and heating elements in the battery compartment. So if the internal temp is too low, you can start and drive, but you also need to warm up the cells before you start charging. Once you're driving, you have alternator output for the heating elements, and it's easy enough to set up an ECU that looks at internal temp and allows/prevents charging. When I tested my charging system, I added a cheap Chinese temp controller, and was going to put the sensor in the compartment, between the 2 batteries - haven't done it yet, though.

I was just browsing the web and ran into a company I haven't seen before - they say they're manufacturing their batteries in Nevada. This would be another drop-in company, and prices maybe 60% of SmartBattery. Does anybody know anything about them? https://battlebornbatteries.com/about-lifepo4-batteries/. No technical info at all on their site, from what I see after a quick look - kind of a crude website. $900 for a 100Ah battery.
 
Don't most battery packs have a heating element that the charger would use to heat the battery pack in the winter before allowing any charing to occur? Seems that is what the RoadTrek guy told me about their setup.

I just wonder how Tesla handles this situation, you don't have an alternator running on another fuel to provide the electricity to heat the pack before you go driving. But if I can draw from it down to -22 degrees, that would cover MOST driving conditions. They must have a way that when I plug it in they do SOMETHING to allow it to warm the battery with the charging plug before it takes a charge.

-Randy
No, most battery packs do not have any heating element. That's something that some folks have added though for RV installation. Tesla battery packs do have a have liquid heating/cooling system and even maintain the battery temp when the vehicle is parked but automotive drive train batteries are a different beast than what we are talking about here. After my exchanges with StarkPower, I'm operating on their assurances that their batteries will be fine in the sort of temperatures we will encounter.
 

ablock

Member
Don't most battery packs have a heating element that the charger would use to heat the battery pack in the winter before allowing any charing to occur? Seems that is what the RoadTrek guy told me about their setup.
It's by no means universal or even necessarily common. Roadtrek had their packs custom made with heating elements interleaved between the cells in the pack. As others have pointed out, a battery that has even a small amount of load is likely to be at a higher than ambient temperature.

I am working on an accessory module for our Elite BMS that will allow easy logging and remote viewing of temperatures (and other cell data) via the BMS's Modbus connector. That should allow me to collect solid information on the relationship between outside ambient and cell temps.
 

Peter Tourin

2020 Unity RL, ex 2012 Unity MB
I'll be real interested in what you find out. This discussion of load and battery temp has been good to hear - I've been seeing the below freezing charging issue as a big deal, and I just hadn't thought about the fact that the load would bring the cell temp up in cold weather.
 

kcshoots

VanTripping.com
At CampFyre vans we have been installing LiFePO4 batteries in our own vans as well as customers and working closely with our battery vendors on charging and discharging management. All of our batteries have integrated cell management--most high quality lithium batteries have. They only reduce or prevent charging when below a pre-set cell temperature, usually between 25 to 0 degrees F. They do not limit discharge current in these lower temperature ranges, as full discharge rates can be provided. Once battery cells warm up above these thresholds from ether from a discharge, the vehicle warming up, or daytime ambient temps, the batteries will begin to allow charging again. We have yet to see any issues in cooler temperatures, and if we are installing LiPOs in customers that regularly use or store their vehicles in cold temps, we prefer to mount them internally to reduce the time that charging may be limited in the colder temps. We have been preferring to install LiPOs for their many benefits particularly weight, space and longevity over AGMs.
 

wade5979

New member
ablock, I'd be very interested how you Elite BMS module comes out. I recently installed one of those myself and love the video output they use. I ran it to the second camera input of my Pioneer so all the info is right there on the dash radio.
 

ablock

Member
ablock, I'd be very interested how you Elite BMS module comes out. I recently installed one of those myself and love the video output they use. I ran it to the second camera input of my Pioneer so all the info is right there on the dash radio.
Hi Wade. I'll let you know. I found the video output useful for install diagnostics (especially because I had a bad BMS CPU and two bad sense boards), but not so appealing for ongoing use. I prefer IP based systems That allow me to access the data from anywhere.
 

Davydd

Well-known member
There are two issues with lithium ion and cold weather. One is you can damage the batteries if you attempt to charge them in below freezing weather. Ideally they should be about 41F to accept a charge. Two, there is a limit to lithium ion regardless of charge, in use or just storing and that is lithium ion batteries should not be subjected to a -20F. Elite Power Solutions said, "The cells will be damaged if go to -20F and the damage may not be recoverable." That's a caveat and you could niggle about the actual temperature from manufacturer to manufacturer but lithium ion is pretty much the same.

Batteries under load by my observation are about 10 to 20 degree above ambient. I have electric heating pads in an insulation case that prevent my batteries going below 41F. The heating pads do not normally come on until the ambient temperature drops in the low 20s. I have 800ah of lithium lon batteries with 16 cells. I can monitor all 16 cells for individual temperature and voltage in real time and I can monitor when the heating pads are actually on. There are other safe guards as well. The batteries will not take a charge below about 36F. I live in Minnesota so there is a real chance in storing in the winter outdoors the temperature can go below -20F but there is a little leeway and plugged into shore power the batteries will always stay above 41F. This year I've taken to a belts and suspender and will store in a heated garage as well. On the road I am certainly not going to endure -20F nor on but a rare occasion even freezing temperature overnight though I camped continuously below freezing 24/7 for a week down to 0F. The heating pads take about 10ah intermittently so there is no chance of draining our 800ah battery.
 

HarryN

Well-known member
Don't most battery packs have a heating element that the charger would use to heat the battery pack in the winter before allowing any charing to occur? Seems that is what the RoadTrek guy told me about their setup.

I just wonder how Tesla handles this situation, you don't have an alternator running on another fuel to provide the electricity to heat the pack before you go driving. But if I can draw from it down to -22 degrees, that would cover MOST driving conditions. They must have a way that when I plug it in they do SOMETHING to allow it to warm the battery with the charging plug before it takes a charge.

-Randy
Tesla actually immerses the batteries in I believe a recirculating transformer oil to aid in thermal control. If the pack is hot, as is often the case under hard driving conditions, it will actively cool down the pack as needed to manage the temperature, and heats for winter conditions.

Their pack is quite well designed actually for high charge and discharge rates. In some ways though, they have it easier than an RV user because many of their customers drive from location A - B, charging on each end and often staying on the power source anytime that the vehicle is not in actual use. (not always, but often).

I am very impressed with what they have done, but the use conditions are somewhat different than an RV.

RVs systems are constantly providing variable (and multiple) charging sources and charging power levels along with similar things going on in the discharge side.
 

Gamma1966

2013 Chassis /14 Unity MB
Peter, would the 10.25" width of the single 300 amp smart battery fit in the battery compartment?
the volume of the 2 Batteries delivered in my 2014 Unit versus the 200 AHr Smart Batteries are:
Width: 7.09 vs 10.25
Length (10.25 x 2 ) = 20.5" vs. 19.25
Height 10.8" vs. 8.75

So it would probably fit length and height wise without issue.
The width of the LiFePo4 Battery may be problem given all the wires that come thru the middle of the back wall; although they are mostly located near the top of the battery box, and the Smart Battery will be 2" lower than the current Interstate Batteries.
 

Gamma1966

2013 Chassis /14 Unity MB
(07Oct17) - Davydd - Can you provide info on the heating pads in your Lith Bat storage box, i.e. manufacturer, source, etc ?
 

Gamma1966

2013 Chassis /14 Unity MB
I am currently on a 10-week trip along the east coast, spending most of the time in Florida, visiting family and friends and avoiding the freezing weather. Before taking this trip, I replaced my 8 - 6 Volt 225 Ahr AGM batteries with 5 - 12 Volt 150 Ahr Lithium ion batteries. I have attached a write up on the battery system I have installed, for those that are interested. So far, the system is working well, and I am very satisfied with the performance. The battery bank weighs less than half of the old AGM batteries and has about 50% more useable capacity.
The auxiliary alternator with a Balmar MC-214 regulator provides the primary source for recharging the battery bank, supplemented by solar and 64 Amp Lithium Ion battery charger.
I can recommend the Lithionics Battery system for those considering replacing existing lead acid or AGM batteries in their LTV unit.
 

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